1. Field of the Invention
The invention relates to rare earth polymer compositions, optical fibers, optical waveguides, and particularly to optical amplifier waveguides and splitters.
2. Description of the Related Art
Optical communication systems based on glass optical fibers (GOFs) allow communication signals to be transmitted not only over long distances with low attenuation but also at extremely high data rates, or bandwidth capacity. This capability arises from the propagation of a single optical signal mode in the low-loss windows of glass located at the near-infrared wavelengths of 0.85, 1.3, and 1.55 .mu.m. Since the introduction of erbium-doped fiber amplifier (EDFA), the last decade has witnessed the emergence of single-mode GOF as the standard data transmission medium for wide area networks (WANs), especially in terrestrial and transoceanic communication backbones. In addition, the bandwidth performance of single-mode GOF has been vastly enhanced by the development of dense wavelength division multiplexing (DWDM), which can couple up to 160 channels of different wavelengths of light into a single fiber, with each channel carrying gigabits of data per second. Moreover, in a recent demonstration, a signal transmission of 1 terabit (10.sup.12 bits) per second was achieved over a single fiber on a 100-channel DWDM system. Enabled by these and other technologies, the bandwidth capacities of the communication networks are increasing at rates of as much as an order of magnitude per year.
The success of single-mode GOF in long-haul communication backbones has given rise to the new technology of optical networking. The universal objective is to integrate voice video, and data streams over all-optical systems as communication signals make their way from WANs down to smaller local area networks (LANs), down to the curb (FTTC), home (FTTH), and finally to the end user by fiber to the desktop (FTTD). Examples are the recent explosion of the Internet and use of the World Wide Web, which are demanding vastly higher bandwidth performance in short- and medium-distance applications. Yet as the optical network nears the end user starting at the LAN stage, the system is characterized by numerous fiber connections, splices, and couplings, especially those associated with splitting of the input signal into numerous channels. All of these introduce enormous optical loss. To compensate for the unacceptably high loss penalty, current solutions rely on expensive EDFAs that are bulky at fiber lengths of about 40 m. The cost of a typical commercial EDFA can reach many tens of thousands of dollars. Thus, to complete the planned build-out for FTTC, FTTH, and FTTD in the US would require millions of amplifiers and hundreds of billions of dollars.
An EDFA module is made up of a number of key components. One of the most critical components in the module is the erbium doped silica fiber (EDF). Present EDF is limited by low concentrations of erbium atoms, clustering that leads to quenching of photoluminescence, a relatively narrow emission band, a highly wavelength dependent gain spectrum, and an inability to be fabricated in a compact, planar geometry. Efforts have been directed toward the use of other rare earth ions in both fused silica glass hosts and other glasses including fluoride, tellurite and phosphate glasses. To this point, these efforts have been limited by the fundamental materials properties of these glass media with regard to their ability to dissolve rare earth atoms, mechanical properties, thermal stability, and other key properties.
The benefits of the present invention are based on the development of rare earth fluorphosphinate polymer material that have the following preferred properties:
compatibility with a broad range of rare earths that enable coverage of the full 1500 to 1600 nm window (and beyond) using a common host platform; PA1 very high concentrations of rare earth elements without associated quenching and upconversion penalties, allowing for very short lengths of fiber to be used as small as centimeters and less; PA1 very low intrinsic optical loss; PA1 capable of being drawn into single mode optical fiber; and PA1 capable of being cast into films for planar waveguide applications.
Cost effective, compact integrated optics is a preferred solution to this problem, but currently none exists.
It is an object of the present invention to provide novel optical waveguide materials that are easy to process using standard silicon VLSI (very large scale integration) fabrication methods and optical fiber drawing processes.
It is a further objective of the present invention to produce a fiber amplifier and material therefor having low-loss in short and medium distance communications network systems.
It is an object of the present invention to produce an integrated optical component that is a low-loss splitter that combines amplification and splitting of the input light signal while maintaining a high signal-to-noise ratio.